International OPEN ACCESS Journal Of M ode rn Engi neeri ng Re s e arch (I JM ER) | IJMER | ISSN: 2249 –6645 | www.ijmer.com | Vol. 5 | Iss.2| Feb. 2015 | 1|Microstructure Analysis of Inlet and Exhaust Valves used in LPG fueled Retrofitted Spark Ignition Engines Ajay Pandey 1 , R. K. Mandloi 2 1 Department of Mechanical Engineering, MANIT, B hopal, India 2 Department of Mechanical Engineering, MANIT, Bhopal , India I.INTRODUCTIONValves used in LPG fueled retrofitted SI engines operate in a very hostile environment. These valves are not only subjected to high temperatures and pressures; they are subjected to impact loading, thermal stresses, and fatigue loading too. Since pressures and temperatures affecting the valves vary with the type of fuel used and its combustion characteristics, valves are exposed to different dynamic and thermal stresses [1]. The exhaust valve temperature is far more in comparison to an inlet valve and can touch 950°C for a retrofitted LPG fueled engine. Engine valves, being subjected to such high temperature and pressures, are extremely vulnerable against wear and consequent failure. Wear failure of valves is a commonly encountered phenomenon which is aided by fatigue crack growth. The wear mechanism in exhaust valves of heavy duty engines has been found to be a combination of oxidation and adhesive wear [2]. Valves also fail due to surface erosion and corrosion. The erosion - c orrosion of exhaust valves (“valve guttering”) is a recognized failure mode in internal combustion engines [3]. All these failure contributing mechanisms alter the microstructure of valves and metallographic images of these variations can be stitched together to provide an insight into valve behavior and its failure. II.EXPERIMENTAL DETAILS Valve SpecificationsThe valves chosen for this experimental investigation were standard poppet valves used in LPG–run, retrofitted passenger car engines in India. The valve specifications are L/TH/D/1, α 45° (inlet valve) and S/TF/D/1, α 45° (exhaust valve).The inlet valve dimensions are 31.6 mm (D) × 7.0 mm (d) × 110 mm (l) whereas the exhaust valve dimensions are 27.0 mm (D) × 7.0 mm (d) × 119.5 mm (l). Sample Preparation Valve specimens of adequate dimensions for microstructure analysis on Atomic Force Microscope (AFM) are prepared using worn - out and new exhaust and inlet valves. The preparation involves cutting and surface finishing with different grades of emery papers, cloth polishing, and cleaning by acetone solution. Finally, the specimen is dried completely in oven. ABSTRACT: Mechanically operated poppet valves are used, both as inlet and exhaust, for most conventional automotive engines in passenger cars. These valves are subjected to high temperatures throughout their operating cycle. A valve originally designed for a gasoline engine, when used for an LPG fueled retrofitted engine, goes through considerable mechanical damage, corrosion, erosion, wear and tear. It also demonstrates significant changes in its microstructure. This investigation focused on microstructure analysis and quantitative metallography of such inlet and exhaust valves using Atomic force microscopy (AFM) technique. The surface morphology of the valve material was studied and AFM measurements were used for quantitative characterization of the structure as also to gain useful information about crystallographic orientation of individual grains, the formation of cracks, identification of potential crack initiation and fracture sites, etc. A comparative evaluation of microstructure of worn - out valves with new valves was also carried out. Keywords:AFM, LPG, microstructure, poppet valve and surface morphology
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Microstructure Analysis of Inlet and Exhaust Valves used in LPG fueled Retrofitted Spark Ignition Engines
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8/9/2019 Microstructure Analysis of Inlet and Exhaust Valves used in LPG fueled Retrofitted Spark Ignition Engines
Microstructure Analysis of Inlet and Exhaust Valves used in
LPG fueled Retrofitted Spark Ignition Engines
Ajay Pandey 1, R. K. Mandloi2
1 Department of Mechanical Engineering, MANIT, Bhopal, India2 Department of Mechanical Engineering, MANIT, Bhopal, India
I. INTRODUCTION Valves used in LPG fueled retrofitted SI engines operate in a very hostile environment. These valves
are not only subjected to high temperatures and pressures; they are subjected to impact loading, thermal
stresses, and fatigue loading too. Since pressures and temperatures affecting the valves vary with the type of
fuel used and its combustion characteristics, valves are exposed to different dynamic and thermal stresses [1].
The exhaust valve temperature is far more in comparison to an inlet valve and can touch 950°C for a retrofitted
LPG fueled engine. Engine valves, being subjected to such high temperature and pressures, are extremelyvulnerable against wear and consequent failure. Wear failure of valves is a commonly encountered
phenomenon which is aided by fatigue crack growth. The wear mechanism in exhaust valves of heavy duty
engines has been found to be a combination of oxidation and adhesive wear [2]. Valves also fail due to surface
erosion and corrosion. The erosion - corrosion of exhaust valves (“valve guttering”) is a recognized failure
mode in internal combustion engines [3]. All these failure contributing mechanisms alter the microstructure of
valves and metallographic images of these variations can be stitched together to provide an insight into valve
behavior and its failure.
II. EXPERIMENTAL DETAILS
Valve Specifications
The valves chosen for this experimental investigation were standard poppet valves used in LPG – run,
retrofitted passenger car engines in India. The valve specifications are L/TH/D/1, α 45° (inlet valve) and
S/TF/D/1, α 45° (exhaust valve).The inlet valve dimensions are 31.6 mm (D) × 7.0 mm (d) × 110 mm (l)
whereas the exhaust valve dimensions are 27.0 mm (D) × 7.0 mm (d) × 119.5 mm (l).
Sample Preparation
Valve specimens of adequate dimensions for microstructure analysis on Atomic Force Microscope
(AFM) are prepared using worn - out and new exhaust and inlet valves. The preparation involves cutting and
surface finishing with different grades of emery papers, cloth polishing, and cleaning by acetone solution.
Finally, the specimen is dried completely in oven.
ABSTRACT: Mechanically operated poppet valves are used, both as inlet and exhaust, for most conventional
automotive engines in passenger cars. These valves are subjected to high temperatures throughout their operating
cycle. A valve originally designed for a gasoline engine, when used for an LPG fueled retrofitted engine, goes
through considerable mechanical damage, corrosion, erosion, wear and tear. It also demonstrates significant
changes in its microstructure. This investigation focused on microstructure analysis and quantitative metallography
of such inlet and exhaust valves using Atomic force microscopy (AFM) technique. The surface morphology of the
valve material was studied and AFM measurements were used for quantitative characterization of the structure as
also to gain useful information about crystallographic orientation of individual grains, the formation of cracks,
identification of potential crack initiation and fracture sites, etc. A comparative evaluation of microstructure of worn
- out valves with new valves was also carried out.
Keywords: AFM, LPG, microstructure, poppet valve and surface morphology
8/9/2019 Microstructure Analysis of Inlet and Exhaust Valves used in LPG fueled Retrofitted Spark Ignition Engines